1. Field of the Invention
The present invention relates to information handling systems and more particularly to a process for producing replicas from a master matrix and to the mold and replicas produced from the process.
2. Description of the Prior Art
Over the years, there has been a continuing attempt to achieve a low cost, mass produced disc which contains video information that can be retrieved with an inexpensive home instrument for playback for a conventional television set.
Early attempts at providing video information have generally involved the use of video tape recorders of various sorts as well as photographic techniques. Still other approaches have attempted to utilize thermoplastic records or the surface alteration of a thin metallic film.
In the co-pending application of Manfred H. Jarsen, Ser. No. 402,636, filed Oct. 1, 1973, entitled "Method of Creating a Replicating Matrix and the Matrix Created Thereby", assigned to the assignee of the present invention, methods were taught which led from a master video recording, such as in the co-pending application of John S. Winslow, Ser. No. 333,560, filed Feb. 20, 1973 now abandoned and continued as Ser. No. 508,815, filed Sept. 24, 1974, and assigned to the assignee of the present invention, to a three-dimensional matrix from which replicas can be created.
In the co-pending Jarsen application, supra, the present casting process was disclosed for producing a replica on a disc which includes a Mylar polyester film substrate and a polymer layer, into which is molded the information contained in the matrix.
According to the present invention, the casting process includes the production of a principal mold which can be used to produce submatrices which, in turn, would produce submolds. Both the molds and the submolds can be used to "cast" replicas. In the preferred embodiment of the process, a Mylar substrate of thickness from 4-10 mils is uniformly coated with a very thin (approximately 3-7 microns) layer of a polymerizable resin to which a catalyst has been added.
The resin is then brought into contact with the mold and subjected to pressure to assure that the resin fills all of the depressions and/or cavities of the mold. The resin is then permitted to cure. The bond between the Mylar substrate and the resin is perfected. After curing, the Mylar and polymerized resin are a unitary structure and, as such, can be peeled from the mold. The same mold can then be used again in the casting of subsequent replicas using substantially the same techniques.
The replica, thus cast, is then provided with a reflective, metal layer, for example, through a vapor deposition process. If desired, an outer, wear layer of clear plastic can be applied.
In the video disc systems described in the related patents and applications, one systems approach permits the use of a thin, flexible disc, such as is produced by the present method. Such a disc can be read on appropriate playback equipment as has been heretofore disclosed.
If, the exigencies of mass production are such that insufficient molds can be derived from a single matrix, it is feasible, according to the present invention, to cast a number of polymer, replicas in the first mold which can function as submatrices, as well.
An alternate replica can be made from an acrylic-polyester combination. The acrylic replicas when plated, can be distributed as such. The acrylic replicas could also be utilized as a starting element in the series of plating steps that ultimately result in a stamper for use in the alternative, stamping process of producing replicas.
In yet other, alternative casting methods, replicas can be produced by first flowing the resin-catalyst mixture into the mold. The Mylar polyester film substrate is applied later, and becomes bonded to the cured resin.
The replica is then "peeled" off the mold. In the preferred embodiment, the cast replica is then subjected to a metallizing step in which a suitably reflective metal such as aluminum is applied to the surface. Vapor deposition of aluminum has been found to be satisfactory. The reflective coating enhances the optical contrast between the deformed areas representing information and the plane areas adjacent thereto. An additional coating of a clear plastic, wear layer can be applied to protect the metal film from scratches or abrasions.
It is obvious that the present method could be modified to produce replicas in which the surface deformations are depressions rather than elevated portions, should that type of replica better lend itself to the playback equipment. Further, the requirements of the playback equipment would also determine the size and shape of the surface deformations which represent the video information.
For example, in the system being developed by the assignee, a reading technique is employed which utilizes light scattering and light reflection to generate electrical signals of different significance. In such a system, the "bumps" or "depressions" serve to scatter rather than reflect light applied from the player device. The surface between adjacent bumps or depressions, however, serves as a plane reflector, and returns substantially all of the light to the player optical system.
In the alternative schemes, phase contrast optics are employed in which case it is desirable that reflecting planes be spaced apart by n.lambda./4 (where .lambda. is the wavelength of the playback radiation and "n" is an odd integer) be employed so that light reflected from a one of the surfaces is constructively interfered with, and light from the other of the surfaces is destructively interfered with.
Given an original matrix having such characteristics, the present process is admirably suited to produce replicas utilizing the mold of the present invention, that is created from the matrix.
The novel features which are believed to be characteristic of the invention, both as to organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which several of the preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.